Bats and Tequila

Bat-plant interactions not only provide a real-life example of coevolution, but they also provide some economic benefits for humans. Agave plants are succulent, cactus-like plants that are used in the production of tequila. They occupy semi-arid deserts of southern North America and northern Central America, and rely on nocturnal animal visitors for pollination (Figure 1; Kunz and Fenton 2003). Tequila production is a multi-billion dollar per year industry and occurs mainly in Mexico, where agave columnar cacti are extremely abundant (Arita and Wilson 1987). For many Mexican workers, agave cacti represent a way of life and contribute substantially to economic stability in Mexico (Arita and Wilson 1987). It has been shown in recent years that nectarivorous bats of Mexican deserts are important pollinators of agaves,  thus represent an important economic and ecological concern for the tequila industry. 

Fig 1. Tuttle, M.D. (2012). Choeronycteris mexicana pollinating an agave plant. Photo retrieved 22/5/2015: Available from http://www.wired.com/2014/06/tequila-booze-and-bats/.

In a field study in Mexico, Arizaga et al. (2000) found that bats were significantly better pollinators of the agave plant Agave macroacantha than were insects; agave plants had significantly more developed fruits following bat visitation. Of three different bat species studied, visitation by Leptonycteris curasoae caused the most fruitset in A. macroacantha (Arizaga et al. 2000). This bat is a highly specialized nectarivore with adaptations to favor nectar extraction from agaves. According to the study, Arizaga et al. (2000) propose that A. macroacantha has developed morphological adaptations, such as forming a "scape" or extended inflorescence, to attract nectarivorous bats and increase the probability of pollen transfer. Since these bats can travel up to 30 km to forage in one night, agaves greatly benefit from bats in that they can reproduce over long distances and maintain population stability (Arita and Wilson 1987). This is yet another example of the incredible coevolutionary adaptations developed by bats and plants to fuel ancient pollination mutualisms. 

References

Arita, H. & Wilson, D. 1987, "Long-nosed bats and agaves: the tequila connection", Bats, vol. 5, no. 4, pp. 3-5.

Arizaga, S., Ezcurra, E., Peters, E., de Arellano, F.R. & Vega, E. 2000, "Pollination ecology of Agave macroacantha (Agavaceae) in a Mexican tropical desert. II. The role of pollinators", American Journal of Botany, vol. 87, no. 7, pp. 1011-1017.

Kunz, T.H. & Fenton, M.B. 2003, Bat ecology, Paperback edn, University of Chicago Press, Chicago.